1. Field of the Invention
The present invention relates to image sensing apparatus such as video camera having camera-shake detection function, and more particularly, to an image sensing apparatus that can detect the direction and magnitude of camera-shake according to variation with time of the distribution state of high luminance area in an image sensed picture.
2. Description of the Background Art
Image sensing apparatus are in practical use that detect the direction and magnitude of camera-shake to correct unnecessary motion in the image sensed picture caused by camera-shaking in shooting continuously an object using an image sensing apparatus such as a video camera. Japanese Patent Laying-Open No. 60-143330 discloses a video camera comprising a vibration type angle velocity sensor that obtains electrically the amount of camera-shaking of a video camera by detecting Corioli's force with the sensor, for example.
There is another method of detecting camera-shake that sets a number of sampling points in advance in an image sensed picture for detecting and holding the luminance signal level of each sampling point in a field, followed by detecting the luminance signal level of the peripheral area of each sampling point in the succeeding field, and comparing this with the luminance signal level of the prior field in the corresponding sampling point for specifying the motion vector of the image sensed picture. In other words, by searching for a point in the periphery area having a luminance level equal to that of the corresponding sampling point in the prior field to calculate the direction and distance of the level change from that sampling point as a center point, the motion vector of the object image is specified for each sampling point. Then, by specifying the most frequent occurring direction and distance motion vector out of the many motion vectors in the entire image sensed picture as the motion vector representing the motion of the entire image sensed picture, the motion of the image sensed picture is corrected in accordance with the determined motion vector.
Such methods of camera-shake correction comprise the method of moving the lens or image sensing device (for example, a solid-state image sensing device such as CCD) of the image sensing apparatus in accordance with the detected camera-shake information (motion vector), and the method of moving an area (effective image area) corresponding to a signal read out area from the image sensing device within an area (image sensing area) corresponding to the entire image sensing device, which are both well-known conventional techniques (for example, refer to Japanese Patent Publication No. 1-212078).
The above mentioned methods of camera-shake detection require the provision of a special sensor or a memory of large capacity, which gave a disadvantage that these methods are not so suitable for video cameras for consumer use.